coastal ruins keys 2

[gary cran]

I'm definitely on level 15 and I have no key to open the gate where the skeletons came from although I have burned the rope and dropped the hanging boulder gone into the pit with the pillar but can't move it. Advise please.

[tlr online]

Run down the steps and pick up the torch, light it using the brazier and light the rope holding the boulder.
Stand out of the way as it crashes down to reveal a hole. Climb into the hole and use the crowbar on the gate.